Coordinate measuring instrument

ABSTRACT

A coordinate measuring instrument for measuring a shape or the like of a work to be measured by a relative displacement value between a measuring element (28) and the work (30). The measuring instrument includes displacement detectors (23, 25, 27) for detecting displacement values of the measuring element (28) relative to the work (30) in the directions of X-, Y- and Z-axes and portable detecting units (35, 38) each having a displacement detector, and these detectors are connected to an input circuit (41) of a processing unit (32) in which the data is processed to output the measured value. The detecting units (35, 38) are selectively used depending on portions to be measured of the work.

TECHNICAL FIELD

This invention relates to a coordinate measuring instrument wherein ameasuring element is tridimensionally concerned with a work to bemeasured and the shape or the like of the work is measured from arelative movement value between the both members.

BACKGROUND TECHNIQUES

In recent years, there has been known a coordinate measuring instrumentfor measuring various shapes such as an outer diameter, an innerdiameter of a hole and a center position of the hole of a work, which isrested on a mount, and has become increasingly common and is widely usedfor the measurement and the like of a tridimensional object with highaccuracy.

The general construction of the coordinate measuring instrument of thetype described has heretofore been one as shown in FIG. 3 for example.More specifically, in FIG. 3, a pair of supports 3 are erected from amount 2 formed of a stone surface plate or the like rested on a supportbase 1, a transverse member 4 made smoothly movable by an air bearing orthe like in the longitudinal direction, i.e. the direction of Y-axis ismounted onto these supports 3, and a relative movement value between thetransverse member 4 and one of the supports 3 is detected by a Y-axisdisplacement detector 5 comprising an optical displacement detector orthe like.

A slider 6 is provided on the transverse member 4 in a manner to be madesmoothly movable by an air bearing or the like in the lateral direction,i.e. the direction of X-axis, and a relative movement value between thisslider 6 and the transverse member 4 is detected by an X-axisdisplacement detector 7 comprising an optical displacement detector orthe like. A square shaft-shaped spindle 9 provided at the bottom endthereof with a measuring element 8 is supported by the slider 6 in amanner to be made slidable by an air bearing or the like in the verticaldirection, i.e. the direction of Z-axis, and a relative movement valuebetween this spindle 9 and the slider 6 is detected by a Z-axisdisplacement detector 10 comprising an optical displacement detectorsimilar to the above-mentioned detectors. Here, the transverse member 4,the slider 6 and the spindle 9 constitute a measuring element supportmember 11. In consequence, the measuring element 8 is supported by themeasuring element support member 11, and the measuring element 8 issupported in a manner to be made movable relative to a work 12 to bemeasured, which is rested on the mount 2, tridimensionally, i.e. in thedirections X-, Y- and Z-axes.

With the above-described arrangement, a shape or the like of the work 12is measured such that: a spindle 9 is manually grasped, or gripped by ahand of a robot in the case of an automatical measurement, and themeasuring element 8 is brought into contact with a preset origin toobtain a reference of polar coordinates; subsequently, the measuringelement 8 is brought into contact with measuring points of the work 12and the relative movement values of this measuring elements from theorigin in the directions of X-, Y- and Z-axes are measured by thedetectors 5, 7 and 10; and signals from the detectors 5, 7 and 10 aresuitably processed by a processing unit comprising a computer or thelike, not shown, to thereby obtain measured values.

Now, in the coordinate measuring instrument of the type described, toachieve the measurement with high accuracy, constructions of variousportions are formed solidly, and the measuring element 8 is integrallysecured to the measuring element support member 11, at a predetermineddistance therefrom. In consequence, the conventional coordinatemeasuring instrument presents the following disadvantages.

(1) In order to move the measuring element 8 to a desired measuredsurface of the work 12, the measuring element 8 should necessarily bemoved together with a moving mechanism as a whole, i.e. the measuringelement support member 11, and moreover, depending on the shape of thework 12, the measuring element should be moved, making a detour aroundthe work 12. Thus, the working efficiency becomes low, and further,there is a possibility of causing damages to the measuring element 8 dueto a collision of the measuring element during the detour.

(2) As in the case where the work 12 has a protruding portion and aportion formed at the undersurface of this protruding position ismeasured, there may occur a surface to be measured, against which themeasuring element 8 cannot abut or cannot easily abut. In such cases,deliberate works may be required or works of remounting the work 12 forchange in its posture may be needed.

(3) As in the case of measuring the dimension of a hole, where thethickness or position does not matter much, but only the diameter of thehole is objected, the portions to be measured include many points notrequiring a positioning in the absolute coordinate system, i.e. thedistance from the origin, however, all of these measurements are carriedout by moving the measuring element 8 tridimensionally in the samemanner as in the conventional example.

As described above, all of the above-described disadvantages lower theworking efficiency. As the scope of application to objects to bemeasured is expanded and the shapes of the objects become complicated,these disadvantages have become important factors to impede the spreadof the coordinate measuring instrument unless these disadvantages areobviated.

Additionally, the coordinate measuring instruments need not necessarilybe limited to the shape shown in FIG. 3 and have various types includingone in which gate-shaped columns are slidably mounted on the mount, onein which the measuring element support member is formed into acantilever beam shape, and further, one in which the mount is mademovable in the direction of Y-axis. However, the above-describeddisadvantages are common to the coordinate measuring instruments of alltypes.

The present invention has as its object the provision of a coordinatemeasuring instrument wherein the measurement suitable for thecharacteristics of the portion to be measured of the work can beperformed and the measuring efficiency can be highly improved.

DISCLOSURE OF THE INVENTION

To this end, the present invention contemplates that: a measuringelement is provided which is movable tridimensionally relative to a workrested on a mount; X-, Y- and Z-axis displacement detectors are providedwhich detect relative movement values of the measuring element to thework in the directions of X-, Y- and Z-axes, respectively; a portabledetecting unit is provided which includes a reciprocatingly movablecontact and a contact displacement detector for detecting a displacementvalue of the contact; the detecting unit and the X-, Y- and Z-axisdisplacement detectors are connected to an input circuit of a processingunit, respectively; and a shape or the like of the work is measured bythe processing unit, utilizing output signals commensurate to therespective axis displacement values of the respective axis displacementdetectors and the output of the detecting unit; whereby the portion tobe measured, requiring the positioning in the absolute coordinate systemis measured by the X-, Y- and Z-axis displacement detectors, and theportion not necessarily requiring the positioning in the absolutecoordinate system, such as the thickness, is easily measured by use ofthe detecting unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general arrangement view showing an embodiment of thecoordinate measuring instrument according to the present invention;

FIG. 2 is a front view showing an embodiment of the detecting unit usedin the present invention; and

FIG. 3 is a perspective view showing an example of the conventionalcoordinate measuring instrument.

THE MOST PREFERRED FORM FOR WORKING THE INVENTION

Description will hereunder be given of an embodiment, in which thepresent invention is applied to the coordinate measuring instrumentdifferent from the conventional one, with reference to the drawings.

In FIG. 1 showing the general schematic arrangement, gate-shaped column22 is rested on a mount 21 comprising a stone surface plate or the likein the longitudinal direction, i.e. the direction of Y-axis, and arelative movement value between one of the column 22 and the mount 21 isdetected by the Y-axis displacement detector 23.

A slider 24 is provided on a top beam of the columns 22 in a manner tobe made movable by an air bearing or the like in the lateral direction,i.e. the direction of X-axis, and a relative movement value between theslider 24 and the column 22 is detected by the X-axis displacementdetector 25.

A square shaft-shaped spindle 26 is provided on the slider 24 in amanner to be made slidable by an air bearing or the like in the verticaldirection, i.e. the direction of Z-axis, a relative movement valuebetween the spindle 26 and the slider 24 is detected by the Z-axisdisplacement detector 27, and a measuring element 28 is detachablymounted to the bottom end of the spindle 26. Here, the column 22, theslider 24 and the spindle 26 constitute a measuring element supportmember 29. In consequence, the measuring element 28 is made movable bythis measuring element support member 29 relative to a work 30 to bemeasured, which is rested on the mount 21, in the directions of X-, Y-and Z-axis, i.e. tridimensionally, these relative movement values aredetected by respective axis displacement detectors 23, 25 and 27, anddetection signals from these detectors 23, 25 and 27 are inputted to aprocessing unit 32 through a respective axis signal cord 31.Furthermore, the detectors 23, 25 and 27 each comprise an opticaldetector or the like emitting a digital signal of one pulse per unitlength of 0.1 micron meter, and can measure with accuracy of 0.1 micronmeter.

A plurality of jacks 33 are provided at predetermined positions on thecolumns 22 and the mount 21, and connected to the processing unit 32through a unit signal cord 34. Furthermore, a plug 37 connected througha cable 36 to a slide caliper type detecting unit 35 or a plug 40connected through a cable 39 to a micrometer type detecting unit 38 ismade connectible to each of the jacks 33, signals of values measured bythese detecting units 35 and 38 are inputted to the processing unit 32through the cables 36, 39, the plugs 37, 40, the jacks 33 and the unitsignal cord 34.

These detecting units 35 and 38 are constructed such that the cables 36and 39 have sufficient lengths for allowing the detecting units toapproach any of the surfaces to be measured of the work 30 rested on themount 21, the dimensions and the like of the surfaces of the work 30 canbe measured with accuracy of 0.1 micron meter, and a digital signal of0.1 micron meter/pulse can be outputted as a measured value, i.e. asignal to be digitally displayed as it is.

The processing unit 32 comprises an input circuit 41, a data processingsection 42 and an output circuit 43. The input circuit 41 can receive aninput signal through a waveform shaping circuit 44 and a counter circuit45 or receive directly depending on the characteristics of the inputsignal. In this case, in this embodiment, since the output signals fromthe X-, Y- and Z-axis displacement detectors 25, 23 and 27 are notwaveform-processed and so on at all, the outputs are inputted throughthe waveform shaping circuit 44 and the counter circuit 45,respectively. Since the detecting units 35 and 38 are provided thereinwith devices for the waveform shaping, the counting and so on, measuredvalues can be outputted as the so-called measured value signals, thesignals can be directly signal-inputted to the input circuit 41.

Signals from the input circuit 41 are suitably processed by the dataprocessing section 42. More specifically, all of the processes necessaryfor the measurements, for example, are performed such that: data of acircle, given as signals of three points are processed to calculate thediameter of the circle or the center position thereof; in which turn thevalue thus calculated is outputted; and further, a mean value iscalculated from a plurality of signals. Signals from this dataprocessing section 42 are outputted to external output devices includinga cathode ray tube 46, a printer 47 and so on, through the outputcircuit 43. Furthermore, when the operation reaches a portion to bemeasured by use of the detecting units 35 or 38, from the output circuit43, there is provided a measurement instructing signal line 48 forinstructing that the detecting units 35 or 38 should be used. A signalfrom this measurement instructing signal line 48 informs the detectingunit 35 or 38 that a predetermined instruction has been given to thedetecting unit 35 or 38.

When the cables 36 and 38 are sufficiently long, the plugs 37 and 40 maybe directly connected to the processing unit 32.

FIG. 2 shows the construction of the micrometer type detecting unit 38in detail. This detecting unit 38 includes a contact 52 reciprocatinglymovably supported on a body 51 and a thimble 53 for reciprocatinglymoving this contact 52, and clamps a portion to be measured of the work30 between the contact 52 and an anvil 54 formed on the body 51, wherebya relative movement between the body 51 and the contact 52 is detectedas the dimension of the portion to be measured by a linear or rotaryencoder as being a contact displacement detector 50, a signal thusdetected is electrically processed, and can be displayed in a digitalindicator 55 as in inches or mm. Furthermore, the body 51 includes: anon-off switch 56 for on-off operating a power source; an inch-millimeterchange-over switch 57 for changing inches for mm or vice versa; a clearswitch 58 for clearing a measured value displayed in the digitalindicator 55; a transmitting switch 59 for transmitting a command todeliver necessary data out of data measured by the movement of thecontact 52 of the body 51 to the processing unit 32; a hold switch 60for holding measured data; a maximum value display switch 61 and aminimum value display switch 62 for selecting the maximum value or theminimum value out of the measured data and displaying the same in thedigital indicator 55; an unit processing circuit 63 for processingsignals from the contact displacement detector 50 so that these switchescan achieve the functions thereof; and a measurement instructing lamp 64as being measurement instructing means for displaying that the detectingunit 38 is in the state of measuring the portion to be measured inresponse to a signal from the output circuit 43 of the processing unit32.

The slide caliper type detecting unit 35, not shown, also has the samefunction as the detecting unit 38 has. In the following description,component parts of the detecting unit 38 are common to those of thedetecting unit 35.

Description will hereunder be given of the method of use of thisembodiment.

In starting the measurement, depending on the shape of the work 30,there are prepared one or plurality of detecting units 35 and/or 38, andthe plugs 37 and 40 of the detecting units 35 and 38 are inserted intothe jacks 33 at positions suitable for the measurement. Subsequently,the switches necessary for the measurement such as the power sourceswitch are thrown in, and the measurement is begun. Similarly to theconventional example, the measurement by use of the measuring element 28is performed such that the measuring element 28 is tridimensionallymoved by the spindle 26 relative to the work 30 rested on the mount 21,and the measuring element 28 is brought into contact with the portion tobe measured of the work 30. The measurement by use of the measuringelement 28 is normally performed in the previously instructed order.However, when it is convenient to measure a portion to be measured byuse of the detecting unit 35 or 38 on the way of the measurement by thismeasuring element 28, a measurement instruction signal is delivered to apredetermined detecting unit 35 or 38, and the measurement instructinglamp 64 is turned on in response to this signal. A measurer performs anecessary measurement by use of the detecting unit 35 or 38 inaccordance with the instruction of lamp thus turned on.

Thereafter, the work 30 is successively measured by use of the measuringelement 28 or the detecting unit 35 and/or the detecting unit 38, andall of the portions to be measured are measured, thus completing themeasurement. Measurement signals detected as described above aredelivered through the input circuit 41 of the processing unit 32 to thedata processing section 42, where the measurement signals are processedin a predetermined mode, and displayed in the cathode ray tube 46 andprinted out in the printer 47 as both members being the output devices,through the output circuit 43.

In this embodiment with the above-described arrangement, the portions tobe measured, which require the positioning in the absolute coordinatesystem, can be measured by use of the measuring element 28 capable ofabsolutely measuring in the same manner as with the conventionalcoordinate measuring instrument, and the portions to be measured, whichshould not necessarily need the positioning in the absolute coordinatesystem can be measured by use of the portable detecting unit 35 and/or38, so that the detecting means can be properly used depending upon thecharacteristics of the work 30 such as the shape, and the workingefficiency in the measurement can be highly improved. There are fewcases where the measuring element 28 should be changed in posture, sothat the working efficiency can be improved from this point too. Recheckof the origin in this case becomes not necessary, the working efficiencycan be improved. Moreover, damages to the measuring element 28 whichwould otherwise be caused by making the detour around the work 30 can beavoided. The detecting units 35 and 38 can be utilized for theadjustment in assembling of the main body of measuring instrument, sothat the manufacturing cost of the measuring instrument can be reduced.Since the detecting units 35 and 38 are of portable type, the work 30can be worked on from all the directions, the undersurface and the likeof the protruding portion of the work 30 can be easily measured, andfurther, the jacks 33 located at convenient positions can be utilized tofurther improved the facility. The results measured by the detectingunits 35 and 38 can be processed in series with the ordinarymeasurements, so that extra data processing works are not necessary andthe data displayed in the cathode ray tube 46 and the printer 47 can beutilized as measured values as they are. Further, when the outerappearances of constructions of the detecting units 35 and 38 are madesimilar to those of the conventional micrometer, slide calipers, depthgauge, hole tester and the like, there should be no feeling ofunusualness as compared with the measuring works by use of theconventional various measuring instruments of this type, so that theworking efficiency can be improved from this point too.

The detecting units 35 and 38 have the transmitting switches 59, wherebyonly the necessary data can be delivered without sending erroneous dataand the like to the processing unit 32, so that no confusion is causedto the processing in the processing unit 32. The detecting unit 38 hasthe hold switch 60, the maximum value display switch 61 and the minimumvalue display switch 62, so that necessary data can be displayed in theindicator 55 on the way of the measurement and changing from inches tomm and vice versa can be performed by the use of the inch-millimeterchange-over switch 57. Furthermore, the detecting units 35 and 38 to beused are given the instructions by the measurement instructing lamp 64,so that an erroneous measurement can be avoided and the measuringefficiency can be improved.

In the above embodiment, it has been described that the X-axisdisplacement detector 25, the Y-axis displacement detector 23 and theZ-axis displacement detector 27 have neither waveform shaping circuitnor counter circuit, while, the detecting units 35 and 38 have thewaveform shaping circuit and the counter circuit, however, the presentinvention need not necessarily be limited to this, and the waveformshaping circuit and the counter circuit may be assembled into therespective axis displacement detectors 25, 23 and 27. Whereas, such anarrangement may be adopted that the waveform shaping circuit and thecounter circuit are not assembled into the detecting units 35 and 38,and signals may be inputted to the input circuit 41 through the waveformshaping circuit 44 and the counter circuit 45, which are provided on theside of the processing unit 32. The coordinate measuring instrumentaccording to the present invention need not necessarily be limited tothe coordinate measuring instrument of the type shown in the embodimentof FIG. 1, and the present invention is applicable to the coordinatemeasuring instrument of the type shown in FIG. 3, the coordinatemeasuring instrument of the type wherein the mount is movable and thecoordinate measuring instruments of other types. Whatever the method ofdriving the measuring element 28 is may be used a manual method, anautomatic method of using a robot, a method of using motors on everyshafts, and so on. Further, the functions of the detecting units 35 and38 need not necessarily be defined by the various switches shown in FIG.2, and the functions may be defined by some of the these switches, orswitches having functions other than the aforesaid switches may be used.Furthermore, the measurement indicating lamp 64 may be replaced byanother instructing means such as a buzzer. The positions of providingthe measurement instructing means need not necessarily be limited to thedetecting units 35 and 38, and the instructing means may be provided onthe external output device such as the cathode ray tube 46 and othercomponents, however, when the instructing means are provided on thedetecting units 35 and 38, it is expedient in the steps of measuring.The output signals from the respective axis displacement detectors 25,23 and 27 and the detecting units 35 and 38 need not necessarily belimited to the digital signals, and may be analogue signals. However,the use of the digital signals is advantageous in that the signals canbe processed easily and the adverse influence of noises can be reduced.Further, in the above embodiment, the detecting units 35 and 38 havebeen connected to the processing unit 32 through the cables 36, 39 andthe cord 34, however, the present invention need not necessarily belimited to this, and the detecting units 35 and 38 may be connected tothe processing unit 32 wirelessly through electric wave, light wave andthe like. The wireless connection as described above can improve thefacility of the detecting units 35 and 38. The term "the absolutecoordinate system" in this specification does not mean that the originson the respective surfaces of X, Y and Z are all derived from one andsame origin. The term contemplates a concept including a case where acoordinate system is shown as referenced from the origins different fromsurface to surface to thereby indicate the positions of the respectiveportions to be measured for example, or a case where a coordinate systemat the time of measurement is converted by the processing unit 32 into asuitable coordinate system to thereby indicate the measured values.

The present invention as described above can offer the advantages ofproviding the coordinate measuring instrument capable of performing themeasurement with high efficiency depending upon the portions to bemeasured of the work.

USABILITY IN INDUSTRIES

The coordinate measuring instrument according to the present inventioncan be utilized for the general field of measuring the shapes and thelike of the works to be measured.

What is claimed is:
 1. A coordinate measuring instrument having ameasuring element supported in a manner to be movable relative to a workto be measured rested on a mount tridimensionally, i.e. in thedirections of X-, Y- and Z-axes, said work having a shape which ismeasured from a displacement value between said work and said measuringelement, comprising:X-, Y- and Z-axis displacement detector means fordetecting the relative displacement values in the directions of said X-,Y- and Z-axes between said work and said measuring element; at least oneportable detecting unit including a reciprocatingly movable contact anda contact displacement detector for detecting a displacement value ofsaid contact; each said X-, Y- and Z- axis displacement detector meansand said contact displacement detector of said detecting unit beingconnected to an input circuit of a processing unit having a dataprocessing section and an output circuit; said output circuit providingoutput signals commensurate to displacement values from each said X-, Y-and Z- axis displacement detector means and said contact displacementdetector of said detecting unit being utilized to make said processingunit able to measure the shape of said work; means defining a pluralityof jacks electrically connected to said input circuit of said processingunit, said jacks being spaced from one another around said mount; andsaid detecting unit being connected through a cable having a plug on anend thereof received in a one of said jacks to said input circuit in amanner to be accessible to any one object surface of measurement of saidwork rested on said mount.
 2. A coordinate measuring instrument as setforth in claim 1, wherein a plurality of said portable detecting unitare provided.
 3. A coordinate measuring instrument as set forth in claim1, wherein said detecting unit is formed to be able to output one pulseper unit length.
 4. A coordinate measuring instrument as set forth inclaim 1, wherein said detecting unit is formed to be able to output ameasured value commensurate to a displacement value of said contact. 5.A coordinate measuring instrument as set forth in claim 4, wherein saiddetecting unit is formed to include a digital indicator for digitallyindicating said measured value.
 6. A coordinate measuring instrument asset forth in claim 1, wherein said detecting unit is formed to includemeasurement instructing means for instructing a measurement by use ofsaid detecting unit.
 7. A coordinate measuring instrument as set forthin claim 6, wherein said measurement instructing means includes meansfor indicating the instruction in said detecting unit by turning on alight.
 8. A coordinate measuring instrument as set forth in claim 1,wherein said detecting unit includes means for selectively deliveringmeasured data to said processing unit.
 9. A coordinate measuringinstrument as set forth in claim 1, wherein a measured value isindicated in an external component.